To detect an object from all sides using optoelectronic sensors and in particular cameras, multi-systems are used that detect the object from different positions and perspectives. If the detection zone of the camera is not sufficient to completely detect the side for which it is responsible, this can be compensated by a relative movement. The object is typically led past the detection system on a conveyor belt for this purpose. A camera line is then also sufficient that stands at an angle to the conveying direction and that assembles image lines detected after one another to form a total view.
Such a system of conveyor belt and a plurality of cameras is also called a camera tunnel. The detection zone is typically protected from environmental light by a mechanical screening. Such camera tunnels can be used for the inspection or measurement of objects. Image processing methods corresponding to the use adjoin the detection. An important area of use is the reading of codes. In this respect, camera-based code readers are increasingly taking over from the earlier barcode scanners. Code regions are identified in the camera images and are then decoded. Camera-based code readers also cope without problem with different code types than one-dimensional barcodes which also have a two-dimensional structure like a matrix code and provide more information. Automatic text recognition (OCR) is also conceivable. Corresponding reading tunnels are used, for example, in the automatic storing and associating of packages, in flight baggage handling or in logistics centers.
In order now to be able to recognize the objects from all sides in a camera tunnel or to be able to read codes everywhere in the case of a reading tunnel, that is to carry out a so-called omnidirectional reading, six cameras are, for example, provided that detect the object from the top and bottom and from both sides obliquely from the front and obliquely from behind. Each camera takes an image of the object, either in one shot or successively by assembling image lines. The images of the lateral cameras also comprise two sides of an object depending on the rotational position of the object. The camera tunnel consequently outputs six images that each show one or more sides of the object. The images are then transmitted over a network, for example. This is, however, relatively complex because a plurality of images for the same object are transferred and evaluated whose information is redundant in part and where the association of an image section to the original location on the object is difficult to access.
An optoelectronic sensor for detecting codes that sectionally reads images of objects moved on a conveyor is known from EP 2 003 599 A1. A first aspect of EP 2 003 599 A1 is the binarization of the detected gray image data or color image data in real time still during the reading in of further sections. Another aspect deals with combining and outputting the information such as raw image data, code regions or results of a decoding in a structured file. Dealing with a plurality of sensors and their different perspectives is, however, not facilitated in this manner.